On the Achievable Bit Rates of DSL Vectoring Techniques in the Presence of Alien Crosstalkers

Executive Summary

Different pre-coder and equalizer structures have been proposed in literature for vectored Digital Subscriber Lines (DSLs). In this paper, the authors assess the relative merit of advanced complex pre-coders and equalizers in practical DSL scenarios. Using extensive computer simulations, the achievable bit rates are investigated in the presence of alien cross-talkers, assuming a beta distribution model for crosstalk couplings. Vectoring in conventional as well as Phantom Mode (PM) VDSL2 transmission is considered. Vectoring techniques at the Access-Node (AN) are studied such as the Zero-Forcing Equalizer (ZFE), ZF Generalized Decision Feedback Equalizer (ZF-GDFE), linear Minimum Mean Squared Error (MMSE), and MMSE-GDFE for UpStream (US) scenarios and Zero-Forcing Precoder (ZFP) for DownStream (DS) scenarios.